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From: Christoph Hellwig <hch@lst.de>
To: Jan Kara <jack@suse.cz>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
	Jens Axboe <axboe@kernel.dk>, Christoph Hellwig <hch@lst.de>,
	Dan Schatzberg <schatzberg.dan@gmail.com>,
	kernel test robot <oliver.sang@intel.com>,
	Jan Stancek <jstancek@redhat.com>,
	linux-block <linux-block@vger.kernel.org>
Subject: Re: [PATCH v2 2/2] loop: use task_work for autoclear operation
Date: Thu, 20 Jan 2022 15:20:14 +0100	[thread overview]
Message-ID: <20220120142014.GA11879@lst.de> (raw)
In-Reply-To: <20220113104424.u6fj3z2zd34ohthc@quack3.lan>

On Thu, Jan 13, 2022 at 11:44:24AM +0100, Jan Kara wrote:
> Maybe the most disputable thing in this locking chain seems to be splicing
> from sysfs files. That does not seem terribly useful and due to special
> locking and behavior of sysfs files it allows for creating interesting lock
> dependencies. OTOH maybe there is someone out there who (possibly
> inadvertedly through some library) ends up using splice on sysfs files so
> chances for userspace breakage, if we disable splice for sysfs, would be
> non-negligible. Hum, tough.

People were using sendfile on sysfs files, that is why support for this
got added back after it was removed for a while as part of the set_fs()
removal.

The real question for me is why do we need freeing and writer counts on
sysfs or any other pure in-memory file system to start with?

  parent reply	other threads:[~2022-01-20 14:20 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-01-07 11:00 [PATCH v2 1/2] block: export task_work_add() Tetsuo Handa
2022-01-07 11:04 ` [PATCH v2 2/2] loop: use task_work for autoclear operation Tetsuo Handa
2022-01-10  6:20   ` Jan Stancek
2022-01-10 10:30   ` Jan Kara
2022-01-10 11:28     ` Tetsuo Handa
2022-01-10 13:42       ` Jan Kara
2022-01-10 15:08         ` Tetsuo Handa
2022-01-12 13:16           ` Jan Kara
2022-01-12 14:00             ` Tetsuo Handa
2022-01-13 15:23               ` Jan Kara
2022-01-14 11:05                 ` Tetsuo Handa
2022-01-14 16:05                   ` Jan Kara
2022-01-13 10:44             ` Jan Kara
2022-01-14 15:50               ` Tetsuo Handa
2022-01-14 19:58                 ` Jan Kara
2022-01-15  0:34                   ` Tetsuo Handa
2022-01-17  8:15                     ` Christoph Hellwig
2022-01-17  9:34                       ` Tetsuo Handa
2022-01-17 14:10                         ` Tetsuo Handa
2022-01-18 15:58                           ` Tetsuo Handa
2022-01-18 16:15                             ` Christoph Hellwig
2022-01-20 14:20               ` Christoph Hellwig [this message]
2022-01-20 15:42                 ` Jan Kara
2022-01-10 16:40         ` Christoph Hellwig

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